The homogeneous precipitation method was used to synthesis ZnO, NiO nanoparticles and ZnO–NiO nanocomposites with and without surfactants, sodium dodecyl sulphate (SDS) and hexamethylenetetramine ...(HMT) to alter the composition of nanocomposites. The grown samples were annealed at 300 °C and 600 °C for 2 h to convert the hydroxides into their oxides. To investigate the effect of different composition on the crystal growth, particle size, morphology, structural and optical properties of nanocomposite, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy (UV), Raman spectroscopy and Scanning electron microscopy (SEM) were employed. X-ray quantitative phase analysis was used to estimate the volume fractions of ZnO and NiO phases in grown nanocomposites. The percentage of ZnO phase is more than NiO phase in all nanocomposites and strongly depends on composition. The structural parameters like lattice constants (a, c), bond-length (l), unit cell volume (v), density (ρ), d-spacing (d), strain (ε) and dislocation density (δ) of ZnO, NiO and ZnO–NiO nanocomposites were calculated. The Scherrer, Williamson-Hall and Size-Strain analysis were used to calculate the crystallite size and lattice strain. The optical parameters such as optical absorption coefficient (α), bandgap (Eg), skin depth (δ), optical density (Dopt), extinction coefficient (k), refractive index (n), optical conductivity (σopt) and dielectric constants (εr, εi) were studied from UV–vis spectra. The nanocomposites grown in this study provide an opportunity of band tuning for better functional performance for device fabrication compared to the basic metal oxides. FTIR characteristic peaks and Raman fundamental optical phonon modes confirmed the formation of ZnO, NiO and ZnO–NiO nanocomposites. SEM analysis revealed that ZnO–NiO nanocomposites have different surface morphology by adding different surfactants.
The PONKCS (Partial Or No Known Crystal Structure) approach has become popular in quantitative phase analysis (QPA) of Portland cements blended with amorphous supplementary cementitious materials ...(SCMs). However, little information on the PONKCS models creation is available. Besides, the small contents and preferred orientation (PO) of calcium sulfate sources (e.g., gypsum and bassanite) can make their accurate quantification difficult in ordinary and blended Portland cements. Our paper brings light to important aspects of XRD QPA that are often neglected/not reported. This was assessed by the production of ordinary and blended Portland cements with clinker, gypsum/hemihydrate, limestone, fly ash, slag, and calcined clay at different proportions. Results showed that backloading preparation was ineffective in preventing PO of alite, gypsum, and bassanite. The March-Dollase function was preferred for PO correction. The space group and background fit used for PONKCS models creation directly affected the method's accuracy. PONKCS yielded good QPA results for binary/ternary blends, except for the simultaneous presence of fly ash and calcined clay.
Pathological calcification in human urinary tract (kidney stones) is a common problem affecting an increasing number of people around the world. Analysis of such minerals or compounds is of ...fundamental importance for understanding their etiology and for the development of prophylactic measures. In the present study, structural characterization, phase quantification and morphological behaviour of thirty three (33) human kidney stones from eastern India have been carried out using IR spectroscopy (FT-IR), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Quantitative phase composition of kidney stones has been analyzed following the Rietveld method. Based on the quantitative estimates of constituent phases, the calculi samples have been classified into oxalate (OX), uric acid (UA), phosphate (PH) and mixed (MX) groups. Rietveld analysis of PXRD patterns showed that twelve (36%) of the renal calculi were composed exclusively of whewellite (calcium oxalate monohydrate, COM). The remaining twenty one (64%) stones were mixture of phases with oxalate as the major constituent in fourteen (67%) of these stones. The average crystallite size of whewellite in oxalate stones, as determined from the PXRD analysis, varies between 93 (1) nm and 202 (3) nm, whereas the corresponding sizes for the uric acid and struvite crystallites in UA and PH stones are 79 (1)–155 (4) nm and 69 (1)–123(1) nm, respectively. The size of hydroxyapatite crystallites, 10 (1)–21 (1) nm, is smaller by about one order of magnitude compared to other minerals in the kidney stones. A statistical analysis using fifty (50) kidney stones (33 calculi from the present study and 17 calculi reported earlier from our laboratory) revealed that the oxalate group (whewellite, weddellite or mixture of whewellite and weddellite as the major constituent) is the most prevalent (82%) kidney stone type in eastern India.
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•FT-IR spectroscopy of kidney stones•PXRD study of urinary calculi•Quantitative phase analysis of kidney stones•Rietveld analysis of PXRD data of renal calculi•Morphological characterization of urinary stones using SEM
Psilocybin {systematic name: 3‐2‐(dimethylamino)ethyl‐1H‐indol‐4‐yl dihydrogen phosphate} is a zwitterionic tryptamine natural product found in numerous species of fungi known for their psychoactive ...properties. Following its structural elucidation and chemical synthesis in 1959, purified synthetic psilocybin has been evaluated in clinical trials and has shown promise in the treatment of various mental health disorders. In a recent process‐scale crystallization investigation, three crystalline forms of psilocybin were repeatedly observed: Hydrate A, Polymorph A, and Polymorph B. The crystal structure for Hydrate A was solved previously by single‐crystal X‐ray diffraction. This article presents new crystal structure solutions for the two anhydrates, Polymorphs A and B, based on Rietveld refinement using laboratory and synchrotron X‐ray diffraction data, and density functional theory (DFT) calculations. Utilizing the three solved structures, an investigation was conducted via Rietveld method (RM) based quantitative phase analysis (QPA) to estimate the contribution of the three different forms in powder X‐ray diffraction (PXRD) patterns provided by different sources of bulk psilocybin produced between 1963 and 2021. Over the last 57 years, each of these samples quantitatively reflect one or more of the hydrate and anhydrate polymorphs. In addition to quantitatively evaluating the composition of each sample, this article evaluates correlations between the crystal forms present, corresponding process methods, sample age, and storage conditions. Furthermore, revision is recommended on characterizations in recently granted patents that include descriptions of crystalline psilocybin inappropriately reported as a single‐phase `isostructural variant.' Rietveld refinement demonstrated that the claimed material was composed of approximately 81% Polymorph A and 19% Polymorph B, both of which have been identified in historical samples. In this article, we show conclusively that all published data can be explained in terms of three well‐defined forms of psilocybin and that no additional forms are needed to explain the diffraction patterns.
The crystal structures of anhydrous psilocybin Forms A and B have been solved using laboratory powder X‐ray diffraction data, refined using synchrotron and laboratory data, and optimized by applying density functional techniques. The crystal structures, along with that of the previously determined trihydrate, permit the quantitative analysis of a variety of historical samples of psilocybin.
This study conducted a quantitative analysis of the martensite/bainite (M/B; bainitic structure region) fraction of martensite-bainite steel using electron back-scatter diffraction (EBSD) analysis. ...The M/B fraction analyzed using the EBSD analysis method was then compared with phase fraction measurement results with an optical microscope (OM), field emission scanning electron microscope (FE-SEM), and field-emission transmission electron microscopy (FE-TEM). In addition, microstructure, tensile and high-cycle fatigue behaviors according to M/B phase fraction were investigated. Initial microstructural observation measured a prior austenite grain size (PAGS) of 24 μm (alloy A) and 11 μm (alloy B). Both alloys were observed to have martensite and bainite structures. XRD phase analysis of the two alloys identified an α-Fe peak expected to be martensite or bainite. Quantitative phase fraction of M/B using EBSD analysis measured M: 40.37% and B: 59.63% for alloy A, and M: 53.03% and B: 46.97% for alloy B. Tensile tests of the above materials confirmed that alloy B, which had finer PAGS and a higher martensite fraction, had greater yield strength (1423 MPa) and tensile strength (1826 MPa) that were approximately 200 MPa higher than alloy A. The yield strength was calculated based on the M/B phase fraction using EBSD and the measured microstructure factors, with a consideration of the prediction model. The calculation value was similar to the actual tested strength one. In the high-cycle fatigue test, alloy B, with its greater strength, had an approximately 200 MPa higher fatigue limit (1075 MPa) than that of alloy A. EBSD analysis of the fatigue crack initiation area confirmed that the M/B interface can act as a fatigue crack initiation site. Based on the above findings, tensile and fracture surface analyses were performed, and attempts were made to identify the tensile and deformation mechanism according to the M/B phase fraction.
A new method for the quantitative phase analysis of multi‐component polycrystalline materials using the X‐ray powder diffraction technique is proposed. A formula for calculating weight fractions of ...individual crystalline phases has been derived from the intensity formula for powder diffraction in Bragg–Brentano geometry. The integrated intensity of a diffraction line is proportional to the volume fraction of a relevant crystalline phase in an irradiated sample, and the volume fraction, when it is multiplied with the chemical formula weight, can be related to the weight fraction. The structure‐factor‐related quantity in the intensity formula, when it is summed in an adequate 2θ range, can be replaced with the sum of squared numbers of electrons belonging to composing atoms in the chemical formula. Unit‐cell volumes and the number of chemical formula units are all cancelled out in the formula. Therefore, the formula requires only single‐measurement integrated intensity datasets for the individual phases and their chemical compositions. No standard reference material, reference intensity ratio or crystal structure parameter is required. A new procedure for partitioning the intensities of unresolved overlapped diffraction lines has also been proposed. It is an iterative procedure which starts from derived weight fractions, converts the weight fractions to volume fractions by utilizing additional information on material densities, and then partitions the intensities in proportion to the volume fractions. Use of the Pawley pattern decomposition method provides more accurate intensity datasets than the individual profile fitting technique, and it expands the applicability of the present method to more complex powder diffraction patterns. Test results using weighed mixture samples showed that the accuracy, evaluated by the root‐mean‐square error, is comparable to that obtained by Rietveld quantitative phase analysis.
A new method for the quantitative phase analysis of multi‐component polycrystalline materials using the X‐ray powder diffraction technique is proposed. The method can derive weight fractions from single‐measurement integrated intensity datasets for individual phases and their chemical compositions. No standard reference material, reference intensity ratio or crystal structural parameter is required.
The quality of X‐ray powder diffraction data and the number and type of refinable parameters have been examined with respect to their effect on quantitative phase analysis (QPA) by the Rietveld ...method using data collected from two samples from the QPA round robin Madsen, Scarlett, Cranswick & Lwin (2001). J. Appl. Cryst.34, 409–426. From the analyses of these best‐case‐scenario specimens, a series of recommendations for minimum standards of data collection and analysis are proposed. It is hoped that these will aid new QPA‐by‐Rietveld users in their analyses.
The step size, angular range and intensity of X‐ray powder diffraction data and the number and type of refinable parameters have been examined with respect to their effect on quantitative phase analysis by the Rietveld method.
In this paper, solution and ageing heat treatment processes were used to improve microplastic deformation behaviors of as-cast SiCp/AZ61 magnesium metal matrix composites (Mg MMCs) fabricated by stir ...casting method. Higher percentages of SiC particle reinforcements showed higher microhardness values. Ageing heat treatment process was seen significant on the 12h aged 2wt% SiCp/AZ61 Mg MMC which induced lower microhardness value. At the 12h ageing of 2wt% SiCp/AZ61 Mg MMC the formations of particle free regions and discontinuous secondary phases were observed. For a higher ageing time, the secondary phases distribution became continuous and laminar structure. The addition of 5wt% SiC particles resulted in the formation of Mg2Si phase throughout the whole heat treatment processes. The addition of SiC particles reinforcements increased the phase heterogeneity during ageing heat treatment processes. XRD patterns revealed the presence of nanocrystalline MgSiO3 phase on the 12h aged 2wt% SiCp/AZ61 Mg MMC. Using reference intensity ration (RIR) method a 51.6% of MgSiO3 phase was determined which can cause the formation of microplastic deformation behavior. And also, the maximum average crystallite size, compressive microstrain and microcrack-free phase boundaries were observed on the 12h aged 2wt% SiCp/AZ61 Mg MMC.
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